1. Field of the Invention
The present invention relates to light emitting medium and an illumination system for transmitting light at one or more wavelengths. The light emitting medium is formed from a translucent or transparent container and a core formed from a mixture which includes an aqueous solution of a water soluble polymer. The illumination system includes an illumination assembly which includes, for example, a light source, such as, one or more light emitting devices (LEDs), a power source, such as a battery, and a switching device, forming a self contained illumination system assembled to a light guide as discussed above. The illumination system may optionally be configured to simulate motion by forming or printing images on the container and selectively switching LEDs of different wavelengths.
2. Description of the Prior Art
Various lighting systems are known using light emitting diodes (LEDs). These lighting systems include LED arrays, clusters, traffic lights and automotive tail lights. LEDs have been the center of focus because of aesthetic, design flexibility, color changing, long life, small physical dimensions and other attributes that together advantageously serve the intended markets. LEDs as a source of light offer many advantages; however, their usefulness is enhanced by the use of optical elements, such as light guides, lenses, refractors, reflectors to disperse, reflect and refract light. As such, LEDs have been combined with various light conduits, such as so called “optical fibers”, “fiber optics”, “light pipes” and “light guides”, collectively categorized as light guides. Lenses, refractors and reflectors among other optical elements are also used to create lighting systems have also been combined with LEDs. These lighting systems find use in markets, such as sign, displays, architectural and transportation.
Light guides are normally made out of polymers, glass, metals or liquids, which require costly raw materials and/or processes. In particular, light guides, such as the ones disclosed in U.S. Pat. Nos. 5,052,778 and 4,957,347, assigned to Lumenyte International Corporation, Irvine, Calif.; U.S. Pat. No. 6,278,827, assigned to Bridgestone Corporation, Tokyo, Japan; U.S. Pat. Nos. 5,406,641 and 5,485,541, assigned to Rohm and Haas Company, Philadelphia, Pa.; and U.S. Pat. Nos. 5,898,810 and 6,535,667, assigned to Minnesota Mining and Manufacturing Company, St. Paul, Minn. and others, are formed from an outer sheath or cladding and a core. A polymer of a higher refractive index material is used for the “core” and a relatively lower refractive index material is used for the “cladding”. Essentially, the cores of such light guides are formed by polymerizing precursor monomers into solid polymers capable of transmitting light efficiently. In many instances, the core is a cross-linked polymer. The cladding is also a polymer of lower refractive index. In general, known light guides all require relatively costly raw materials. Additionally, the apparatus and methods used to manufacture these light guides are cumbersome, capital intensive, and require skilled labor and in some instances are not environmentally sound.
Another class of light guides, for example, as disclosed in U.S. Pat. Nos. 4,261,936 and 5,111,526, assigned to Mitsubishi Rayon Co., Ltd., Tokyo, Japan, are formed with substantially smaller diameters and are produced differently than the light guides discussed above. In particular, to achieve lighting effects, a bundle of such light guides are encased in a plastic sheeting. Unfortunately, these light guides suffer from the same shortcomings as discussed above.
Another type of light guide in the same category, manufactured by the Bridgestone Corporation, Tokyo, Japan and disclosed in detail in U.S. Pat. No. 6,488,397, discloses a light guide with a strip of reflective material placed at the core-clad interface to disperse the light. In such a light guide, the light dispersion is directional, and the material is very rigid and difficult to work with.
In yet another class of light guides, liquid light guides are disclosed. These light guides are normally formed from a thermoplastic cladding and a liquid core. Such liquid light guides fall in two main categories. The first category, used in the medical industry, is intended to transmit light from one point (input end) to the end point (distal end), for example, as disclosed in U.S. Pat. Nos. 5,452,395, 6,418,257 and 6,507,688. The manufacturing processes for the production of this class of light guides is rather specialized and cost prohibitive for many applications. Normally, a very concentrated salt solution is used for the liquid core. In the second category, for example, as disclosed in U.S. Pat. Nos. 5,799,124 and 5,896,483, illuminating systems for decorative applications are presented. In the latter category, the use of liquids is limited to non-aqueous liquids.
In general, the above light guides are used to create an effect. For example, an LED light is used to introduce light into the light guide, such as the polymer light guides disclosed above, to create a “neon effect”. Neon, a commonly known lighting medium, glows from the sides when activated. This effect is known as neon effect. The light guides disclosed in the U.S. Pat. Nos. 5,052,778, 4,957,347, 6,278,827, 5,406,641 and 5,485,541, 5,799,124, 5,898,810 and 6,535,667 in part, disclose such light guides.
In traditional neon illumination systems, a powerful and prohibitively costly halogen, high intensity discharge or xenon lamp is used as a source light. These highly inefficient lamps, along with other related components are normally housed in an enclosure, known as an “illuminator”. These illuminators are notoriously known to be energy-hungry, expensive, bulky, noisy, inefficient, fragile and have a short lamp life requiring costly maintenance. Additionally, the light coupling into the optics was known to be very inefficient and not user friendly. As a result of these deficiencies the growth of the industry has been rather limited.
The light guides discussed above in combination with on or more LEDs have been used to create illumination systems to solve the problems associated with traditional neon light systems. However, the light guides discussed above, due to the relatively high cost of raw materials, are relatively expensive to manufacture and thus are relatively limited in their applications. Thus, there is a need for light guide which can be formed from relatively less expensive raw materials and can be used in a wider range of applications than known light guides.